This invention relates in general to respirators and in particular to a new and useful ventilation system for persons in which there is a ring line having a gas transport device which is a blower which operates continuously to provide a continuous circulation of the gas from a gas supply and to an improved control providing a control flow in inspiration and expiration branches connected to the ring line.
The invention relates to a ventilation system with positive and negative ventilation pressures controllable through a control unit, which pressures are produced by a gas transport element, a ring line being provided which comprises in an inspiration branch an inhalation valve and in an expiration branch an exhalation valve. In addition, an advantageous controllable valve unit for use in such a ventilation system is provided.
From German Pat. No. 917,210 an apparatus for artificial ventilation is known where a ventilation connection is connected via positively coupled valves controlled as a function of pressure in an open system alternately with the intake side and with the discharge side of an injector.
German Pat. No. 946,258 describes a respirator with an inspiration and an expiration branch, which branches are connected to a pressure blower and with a suction blower. By a gate valve control acting in both branches, positive and negative ventilation pressures of appropriate duration are produced. This, too is an open system, which has the disadvantage of high respiratory gas consumption.
Such systems are not usable because of the control sluggishness of their mechanical parts when a relatively high pulse repetition frequency of the ventilation pulses at high slope steepness is to be achieved.
In German AS No. 24 24 025 a ventilation apparatus with inspiration branch and expiration branch is described, which branches form part of a closed cycle conduit. In the inspiration branch there is an inhalation valve, and in the expiration branch, an exhalation valve. For pressure generation there is used a blower of reversible direction of rotation which is connected alternately to the inspiration branch by its pressure side, and after reversal of direction, to the expiration branch by its suction side. Such an arrangement requires a complicated system of reversing the direction of rotation of the blower and is usable only for relatively slow pulse repetition frequencies.